1 Introduction

1.1 Background

SNOMED CT terminology provides a common language that enables a consistent way of indexing, storing, retrieving, and aggregating clinical data across specialties and sites of care.

The International Health Terminology Standards Development organisation (IHTSDO^®) maintains the SNOMED CT technical design, the content architecture, the SNOMED CT content (includes the concepts table, the descriptions table, the relationships table, a history table, and ICD mappings), and related technical documentation.

1.2 Purpose

This document provides a summarized description of the content changes included in the January 2017 release of SNOMED Clinical Terms^® (SCT) International Release.

It also includes technical notes detailing the known issues which have been identified. These are content or technical issues where the root cause is understood, and the fix has been discussed and agreed, but has yet to be implemented.

This document is available as part of the January 2017 International Edition release.

1.3 Scope

This document is written for the purpose described above and is not intended to provide details of the technical specifications for SNOMED CT or encompass every change made during the release.

1.4 Audience

The audience includes National Release Centers, WHO-FIC release centers, vendors of electronic health records, terminology developers and managers who wish to have an understanding of changes that have been incorporated into the January 2017 International Edition release.

• Over 100 new anatomy concepts have been added for representation of different sections of the prostate to support annotation for clinical imaging. The new codes are included in the DICOM subset for structured reporting.

2.2.2 Clinical finding

• 23 new nutrition and dietetics concepts to support clinical documentation, care planning and research for nutrition. 
• 45 new laboratory finding concepts to support microbiology, chemistry and pathology

2.2.3 Convergent Medical Terminologies (CMT)

• New concepts added continuously.

2.2.4 Dentistry

• To continue improvements in coverage of the periodontal domain, over 90 new concepts to support the Dentistry subset have been added. 

2.2.4.1 Cephalometry

• 23 new concepts added for cephalometry a specialist domain for dentistry, subtypes of 698965000|Immaterial anatomical entity (body structure)

2.2.5 Diagnostic Imaging Procedures

• 48 new concepts added for cone beam CT imaging procedures; 
•  23 new concepts added as site specific subtypes of 430447002|Computed tomography for radiotherapy planning (procedure) 

2.2.6  LOINC

• 215 new concepts to support antibody, antigen, DNA and RNA components needed to map to LOINC Parts. 
  
  

2.2.7 Medical Devices

• The medical devices content has been updated to align with the GMDN monthly release up to an including April 2016. This resulted n the addition of 208 new concepts. The linkage to GMDN is provided as a simple mapping file and is also current through the April 2016 GMDN monthly update. Future work will include the resolution of conceptual duplicates.

2.2.8 Organisms

• 250 concepts to support microbiology reporting.

2.2.9 Pharmaceutical/biologic products

• Minor maintenance only.
   

• • Modeling was updated for approximately 60 concepts with pattern |Allergy to X (disorder)| to correct an issue related to inference of more general |Causative agent| attributes. This work will continue with more concepts being updated in a similar manner for the January 2017 release.

2.3.3 Findings

• A number of changes were made as quality improvements based on SIRs requests. 

2.3.4 Substances

• Minor maintenance only

2.3.5 Internal Quality Improvement

• Combined/compound allergy concepts inactivated as ambiguous
• Drug indicated (situation)| sub-hierarchy reviewed and modeling updated.
• Inactivated disjunctive substance concepts

2.4 SNOMED CT derived products

2.4.1 ICD-10 map

The SNOMED CT to the International Statistical Classification of Diseases and Related Health Problems, Tenth Revision (© World Health organisation 1994) 2010 Version map (SNOMED CT to ICD-10 Map) is included in the SNOMED CT International release as a Baseline. The SNOMED CT to ICD-10 Map was created to support the epidemiological, statistical and administrative reporting needs of IHTSDO member countries and WHO Collaborating Centres.

The SNOMED CT to ICD-10 Map is released in Release Format 2 (RF2) only. It is located in the file der2_iisssccRefset_ExtendedMapFull_INT_20160731.txt, which is in the Map folder under Refset, in each of the three RF2 Release Type folders.

The SNOMED CT to ICD-10 Map is released as Refset 447562003 |ICD-10 complex map reference set (foundation metadata concept)|.

2.4.1.1 Content development activity summary

The map is a directed set of relationships from SNOMED CT source concepts to ICD-10 target classification codes.  The SNOMED CT source domains for the MAP are limited to subtypes of 404684003 |clinical finding|, 272379006 |event| and 243796009 |situation with explicit context|.  The target classification codes are ICD-10 2010 release.

2.4.1.2 Mapped content for January 2017

The map provided for the January 2017 release has been updated, and now represents a complete map from SNOMED CT International release to ICD-10 2010 version. We would welcome feedback on any issues that users of the map may detect when using the map. Issues should be submitted via mapping@ihtsdo.org

2.4.2  ICD-9-CM map

IHTSDO produced a SNOMED CT to ICD-9-CM Epidemiological and Statistical Map with each SNOMED CT International Release. The artifact provided a map from a clinical statement expressed in SNOMED CT to a target code(s), or in some cases no target, in the ICD-9-CM classification. The SNOMED CT to ICD-9-CM Epidemiological and Statistical Map includes maps from the SNOMED CT Clinical Findings to ICD-9-CM 2012, the last updated version.

The World Health organisation stopped maintenance of ICD-9 in the 1990s when ICD-10 came into use by the WHO Member States. The United States (U.S.) National Center for Health Statistics (NCHS) is responsible for maintenance of the clinical modification (CM) of ICD-9. The last regular, annual update to ICD-9-CM code was on October 1, 2011.

In view of the legacy nature of the classification, a deprecation process has been followed, to remove the SNOMED CT to ICD-9-CM Epidemiological and Statistical Map from the International edition.    The deprecation notice and documents can be found here:  https://confluence.ihtsdotools.org/display/PL/Deprecation

The SNOMED CT to ICD-9-CM map has therefore been deprecated without support, as of the July 2016 International edition. The Static version of the map (based on the January 2016 content) is available on the IHTSDO MLDS distribution site (https://mlds.ihtsdotools.org/#/ihtsdoReleases), for any users who wish to access it during their transition to SNOMED CT or ICD-10-CM.

3 Technical notes

3.1 Known Issues

Known Issues are content or technical issues where the root cause is understood, and the resolution has been discussed and agreed but has yet to be implemented.  This can be due to a number of reasons, from lack of capacity within the current editing cycle, to the risk of impact to the stability of SNOMED CT if the fix were to be deployed at that stage in the Product lifecycle.  

For the Snomed CT July 2016 International edition, the following Known Issues were identified, and agreed to be resolved in the next editing cycle (to be published in January 2017):

3.2 Resolved Issues

Resolved issues are Known Issues which were not fixed as part of the previous release lifecycle, but which have now been resolved in the latest release - in this case the July 2016 International Edition.  They can also be issues found during the Alpha and Beta testing of the current release, which were resolved before the final deployment of the associated Member release.  Finally they can be issues which were reported or found during the testing phase, but which have been closed without any action taken.  

The Resolved Issues for the Snomed CT July 2016 International edition can be found here:

3.3 Technical updates

Complex map files

In line with the ICD-9-CM deprecation process described in section 2.4.2 above, the complex map files have been removed from the RF2 release package.  This is because the ICD-9-CM map constituted the entirety of the complex map files, and as this map has now been deprecated, there is no longer a use case to include the complex map files.  The same applies to the ICD9 CrossMaps files in the RF1 package, which have been removed for the same reason.

RF1 package

In line with the RF1 deprecation plan approved by the General Assembly in October 2015, IHTSDO will take a new approach to generating qualifying relationships in the RF1 distribution of the SNOMED CT International Edition.

The scope of qualifying relationships in the July 2016 International Edition will be limited to Lateralization Qualifying Relationships in the Body Structure hierarchy. The conversion utility will take a RF2 Laterality reference set as its input.  The RF2 Laterality reference set will be available from the IHTSDO Licensing and Distribution system (MLDS). The approach also removes qualifiers not related to body structures because these cannot be reproduced algorithmically. This approach is required so that the new algorithmic derivation of RF1 files from the authoritative RF2 distribution can be run independently of IHTSDO from 2017 onwards.

File types now removed from the RF1 package

The following files will be removed from the RF1 package, as they are incompatible with the new algorithmic RF1 conversion process, which (as detailed above) needs to be self-contained going forward:

• res1_DualKeyIndex_Concepts-en-US_INT_[date].txt
• res1_DualKeyIndex_Descriptions-en-US_INT_[date].txt
• res1_WordKeyIndex_Concepts-en-US_INT_[date].txt
• res1_WordKeyIndex_Descriptions-en-US_INT_[date].txt
• res1_Canonical_Core_INT_[date].txt
• der1_CrossMaps_ICDO_INT_[date].txt
• der1_CrossMapSets_ICDO_INT_[date].txt
• der1_CrossMapTargets_ICDO_INT_[date].txt

Resource Filename update

The naming convention for the Stated Relationship to OWL resource file has been updated from “tls2_StatedRelationshipsToOwlKRSS_INT_[date].pl” to “tls2_StatedRelationshipsToOwlKRSS_Script_INT_[date].pl”

RF2 package format

For future reference, the RF2 package convention dictates that it contains all relevant files, regardless of whether or not there is content to be included in each particular release.  Therefore, the package contains a mixture of files which contain both header rows and content data, and also files that are intentionally left blank (including only a header record).  The reason that these files are not removed from the package is to draw a clear distinction between

1. ...files that have been deprecated (and therefore removed from the package completely), due to the content no longer being relevant to RF2 in this or future releases, and 
2. ...files that just happen to contain no data in this particular release (and are therefore included in the package but left blank, with only a header record), but are still relevant to RF2, and could therefore potentially contain data in future releases.

This allows users to easily distinguish between files that have purposefully been removed or not, as otherwise if files in option 2 above were left out of the package it could be interpreted as an error, rather than an intentional lack of content in that release.